So our cat 13 yr old has been throwing up now and then. Took him to a vet close to us that has seen our tortoise. Did bloodwork came back normal. We feed the cat meal that Just for Dogs makes, which is fish and chicken, good food. So this vet recommended we change his diet to hydrolized purina cat kibble. My son is having a fit, saying go from good food to kibble? Maybe we should just stick to this vet for the tortoise he is a good reptile vet. Thinking of calling and say pass on this food.?

I would absolutely not switch to kibble - any kind of kibble - for a 13 year old cat. One thing that every vet I've ever used drilled into my head is that cats, especially seniors, should be on wet food, and that even young ones should receive some wet food every day.
When my cats occasionally threw up, I added a container of cat grass (oat grass or wheat grass) to their feeding area. Usually they would cough up or pass in their stool a hairball within two days and then be good for months. With my last cat, Allie, I made sure she always had oat or wheat grass available.
You may wish to feed smaller meals more frequently, removing the dish after twenty minutes or so. I found this seemed to help minimize any vomiting. Also, to encourage water consumption, put the water dish somewhere different from the food dish - apparently they don't like them side by side. My cat greatly increased her water intake (and therefore her overall skin and digestion conditions) when I learned this several years ago.

Thanks Emma's Mom. Tony turns 14 right after the new year, so he's no spring chicken, but he's been well taken care of food wise. I added pumpkin to his food and gave smaller amounts. He hasn't thrown up since. This vet peeked in his mouth with a micro flashlight, said he was missing teeth and had a root tip. But before we left he says something about having his teeth cleaned, not a word about surgery. Watching Tony eat he seems to favor one side of his mouth eating, chances are he has mouth pain. A kibble would not be good for a sore mouth. Odd thing is when he mentioned the teeth issue I though ugh oh sounds like we are going to make a car payment for him and and was expecting a tech to come in with a estimate of costs. Didn't happen. Just change to kibble. Ugh! Will be looking for another vet. But I don't recall seeing teeth spit out around the house, or he might be genetically missing teeth, he is a small cat maybe he hid his teeth from me, expecting the kitty tooth fairy to come? LOL

Certainly sounds like it could be mouth pain, if a root tip is exposed and he is eating on one side. Cats (and dogs) often just swallow teeth when they fall out, so it isn't surprising you didn't see the missing tooth. But time for a new vet, for sure.